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Re: Managing Co-reference (Was: A Semantic Elephant?)

From: Aldo Gangemi <aldo.gangemi@cnr.it>
Date: Wed, 14 May 2008 23:24:38 +0200
Cc: Aldo Gangemi <aldo.gangemi@cnr.it>, Tim Berners-Lee <timbl@w3.org>, Sören Auer <auer@informatik.uni-leipzig.de>, Semantic Web Interest Group <semantic-web@w3.org>, Chris Bizer <chris@bizer.de>, Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>, Kingsley Idehen <kidehen@openlinksw.com>, "Fabian M. Suchanek" <f.m.suchanek@gmail.com>, Tim Berners-Lee <timbl@csail.mit.edu>, Jim Hendler <hendler@cs.rpi.edu>, Mark Greaves <markg@vulcan.com>, georgi.kobilarov@gmx.de, Jens Lehmann <lehmann@informatik.uni-leipzig.de>, Richard Cyganiak <richard@cyganiak.de>, Frederick Giasson <fred@fgiasson.com>, Michael Bergman <mike@mkbergman.com>, Conor Shankey <cshankey@reinvent.com>, Kira Oujonkova <koujonkova@reinvent.com>
Message-Id: <8E6AE28E-15C9-4355-9D0A-52B15C8BD54F@cnr.it>
To: "Michael F Uschold" <uschold@gmail.com>

> 	• Problem 2) even if you can find the links, prolific use of  
> owl:sameAs will create computational problems.
>


Michael,

there is an item related to Problem 2), already discussed on LOD and  
elsewhere last year, i.e. the use of
owl:sameAs, which is a formal relation of identity, to denote generic  
"similarity", or even "relatedness"
between two entities.

owl:sameAs is great to co-reference persons, places, etc. It is buggy  
when used to relate e.g. foaf:Person
instances to persons' homepages, or a city as from Cyc to a wikipedia  
article of that city (as done in DBpedia).

In previous discussions, besides some weak good practices [1], I found  
no attempt to discourage its use for similarity.
This use is not needed. We can use e.g. rdfs:seeAlso, skos:related, or  
any other local relation instead.

It is reasonable, as Richard Cyganiak wrote at the time, that we have  
to work around the quirks [2],
nonetheless, if there is no real need, why should we work around the  
quirks caused by a pointless identity
assumption?

Notice that ignoring owl:sameAs is not a good solution. We need some  
trade-off between simplicity
and formality. A basic similarity relation is perfect, and then those  
triples can be worked out automatically,
by means of appropriate metamodels, e.g. as proposed in [3].

Aldo

[1] Bernard Vatant suggested some good practice of mutual linking:
http://universimmedia.blogspot.com/2007/07/using-owlsameas-in-linked-data.html

[2] Cyganiak quote:
> People who want to re-use your data will learn to work around its  
> quirks and idiosyncrasies.
> Dealing with the quirks is a part of re-using data, it always was,  
> and it always will be.
>

[3] http://www.ibiblio.org/hhalpin/irw2006/vpresutti.pdf from IRW  
workshop: http://www.ibiblio.org/hhalpin/irw2006/


_________________________________

Aldo Gangemi

Senior Researcher
Laboratory for Applied Ontology
Institute for Cognitive Sciences and Technology
National Research Council (ISTC-CNR)
Via Nomentana 56, 00161, Roma, Italy
Tel: +390644161535
Fax: +390644161513
aldo.gangemi@cnr.it

http://www.loa-cnr.it/gangemi.html

icq# 108370336

skype aldogangemi
Received on Thursday, 15 May 2008 08:18:59 GMT

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